1. Field of the Invention
The present invention relates to the specific depolymerization of a polysaccharide having a rod-like helical conformation.
2. Description of the Prior Art
Several viscous polysaccharides such as xanthan, lentinan, schizophyllan, scleroglucan or curdlan, have been found to have two or three stranded helical structures. (T. Norisuye, et. al; J. Polymer Science, Polymer Physics Ed. 18, 547-558 (1980): E. D. T. Atkins and K. D. Parker; J. Polymer Science Part C. 28, 69-81 (1969); T. L. Bluhm and A. Sarko; Can. J. Chem. 55, 293-299 (1977): R. H. Marchessault, et. al; Can. J. Chem. 55, 300-303 (1977): E. R. Morris; A.C.S. Symposium Series, n, 45, 81 (1977): E. R. Morris, et. al; J. Mol. Biol. 110, 1 (1977)). Exploitation of the potentials of these polysaccharides has been investigated and some were developed as thickening agents for food industry based on their high viscosities, and others were found to have potent, host-mediated anti-tumor activities. But in some cases, the extremely high viscosities of their solutions make their utilizations difficult.
In order to reduce their viscosities properly, we invented an ultrasonic method for depolymerization of the polysaccharides. (Japanese Patent Laid open No. (Kokai) 57335/1977) Our investigations on the mode of the ultrasonic depolymerization confirmed that it is caused mainly by the cleavages of the main chain of the polysaccharide and that neither side chain nor carbon-carbon bond in glucose residue is cleaved during the sonic depolymerization. Thus, the resulting degraded polysaccharide consists of the same repeating unit and also has the same helical conformation, as those of the original polysaccharide.
Recently, we found that the ultrasonic depolymerization method is not suited for industrial depolymerization of a large bulk of polysaccharide, because of its low efficiency. The ultrasonic depolymerization method is also involved in high noise-level and erosion of the vibrating rod of the ultrasonic oscillator.